That is just your perception of value though. You aren't placing a value of nearly £100 on the cost of getting from Taunton to London.If I want to get a train to Taunton from London and I walk up to the booth, I cannot conceive of how it should cost nearly £100.
Surely it should be price per distance traveled, irrespective of timing. It is a public service.
The natural conclusion I might reach faced with a fare of nearly £100 to get from Taunton to London is not to make the journey. Some people choose to go by coach instead. However, that is not the conclusion that everyone reaches and many pay that fare. The cost to the railway to provide that seat may well be nearly £100.
Just thinking about the 142 mile journey from Taunton to London, 284 miles return, how does someone determine whether £50, £100 or £150 is the right walk up fare? Should it be the price at which trains are full on a Saturday morning, full from Taunton, or still room for people to board nearer London?